CAIRO (AFP) - Gunmen on Sunday shot dead two wounded members of Egypt's security forces in an ambulance after they had been injured by a bombing in the Sinai Peninsula, security officials said.

A medic in the ambulance was also killed in the ambush in the town of Sheikh Zuweid in North Sinai, where the ISIS (Islamic State in Iraq and Syria) group is spearheading an insurgency.

Inside the ambulance were three security personnel who had been wounded just minutes previously in a blast targeting their armoured vehicle, a senior security officer in El-Arish said.

"When the ambulance left the site of the blast with the wounded security members it came under attack from gunmen," the officer said, speaking on condition of anonymity.

"Two wounded security personnel and a medic were killed in the ambush," he said, without specifying whether the dead were in the police or army.

Mahmud Amer, head of the North Sinai ambulance service, confirmed the death of a medic in an attack in Sheikh Zuweid but did not elaborate.

No militant group has yet claimed responsibility for either the bomb attack or the subsequent ambush.

Extremists from "Sinai Province", Egypt's ISIS affiliate, are waging an insurgency in the restive peninsula that has killed hundreds of soldiers and police since the army overthrew Islamist president Mohamed Morsi in 2013.

ISIS also claimed the October 31 downing of a Russian airliner carrying tourists over Sinai that killed all 224 people on board.

The group said it had smuggled a bomb on board at an airport in the south of the peninsula.

The Sinai extremists pledged allegiance in November 2014 to ISIS, which controls parts of Iraq and Syria and also has a presence in conflict-ridden Libya.

Egypt's military, meanwhile, said in a statement on its Facebook page that in a separate incident on Sunday, "terrorists had opened fire on a group of security forces in Sheikh Zuweid, and in an ensuing gunfight five terrorists had been killed".